How to Use the Referrer-policy to Limit Referrer Data in Analytics and Logs

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Understanding how websites share referrer information is important for privacy and security. The Referrer-Policy HTTP header allows website owners to control how much referrer data is sent when users navigate from one site to another. Proper use of this policy can help limit the exposure of sensitive information in analytics and server logs.

What is the Referrer-Policy?

The Referrer-Policy is an HTTP header that specifies how much referrer information should be included with requests. It can be set to various values, each offering different levels of privacy. By configuring this header, website administrators can prevent the accidental sharing of sensitive URLs or data.

Common Referrer-Policy Values

  • no-referrer: No referrer information is sent with requests.
  • no-referrer-when-downgrade: Default; no referrer sent on HTTPS to HTTP transitions.
  • origin: Only the origin (domain) is sent as referrer.
  • strict-origin: Sends the origin only over HTTPS.
  • same-origin: Only send referrer if navigating within the same site.
  • strict-origin-when-cross-origin: Sends full referrer on same-site requests, but only origin on cross-site requests over HTTPS.
  • no-referrer-when-downgrade: Default behavior, balancing privacy and analytics needs.

Implementing the Referrer-Policy

The policy can be set via server configurations, HTML meta tags, or HTTP headers. For example, to set it in your website’s HTTP headers, you might add the following to your server configuration:

Referrer-Policy: no-referrer

Using Meta Tags

If server configuration is not an option, you can include a meta tag in your HTML:

<meta name="referrer" content="no-referrer">

Best Practices

  • Choose a policy that balances privacy with your analytics needs.
  • Test your website after implementing changes to ensure functionality.
  • Combine with other security headers for comprehensive protection.

Impact on Analytics and Logs

Limiting referrer data reduces the amount of sensitive information sent to analytics platforms and stored in server logs. This can help protect user privacy and comply with data protection regulations. However, it may also limit the insights you gain from referral data, so choose your policy carefully based on your needs.

By properly configuring the Referrer-Policy, you can enhance your website’s privacy controls while maintaining essential analytics functions.